This has been bothering me more lately for some reason...The older boxes had a defeatable Dolby Volume option in Setup that seemed to do a pretty good job of leveling the volume between HD & non-HD channels. With this newer XG1 box there's no Dolby Volume option in the settings menus & no other Audio Compression settings that I can find. Switching between HD channels & non-HD's can result in pretty dramatic volume shifts (I'm using the HDMI Audio Out from the box to feed a Yamaha 7.1 channel receiver). And to a lesser extent between certain HD channels as well.
In playing around with all settings, this is related to those quieter non-HD's transmitting Stereo PCM audio instead of DD. The Yamaha does have its own digital compression for audio but it's not enough to level these volume differences. I do notice that when I change the Audio Mode setting of the cable box from Surround (which sounds best with DD audio) to Stereo, the audio feeds from those non-HD channels sound significantly better since this matches what's being transmitted & the Yamaha can then properly apply its own sound field settings.
Problem is that this setting applies to everything & it's a pain to manually switch the Audio between Surround & Stereo depending on the channel being watched. Also, in Surround mode the Yamaha reports receiving a DD audio signal from the box for these same non-HD channels, suggesting that the box is converting the actual Stereo feed into DD under that setting.
All of this is leading me to believe that this box doesn't employ Dolby Volume, or for that matter any other audio compression scheme. I'm wondering what Comcast's future plans are in the way of volume levelling, especially with X2 & upcoming IP-only boxes. Seems like not including a feature like Dolby Volume (especially one that's user-defeatable via user Settings) was a step backwards from prior technology.
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